As rubbers for automobile tires, conjugated diene rubbers (e.g., styrene-butadiene copolymers) obtained by emulsion polymerization methods or solution polymerization methods have been hitherto known. In recent years, it has been required to further improve low fuel consumption performance of automobiles, and various conjugated diene rubbers for realizing excellent low fuel consumption performance have been proposed. For example, as a rubber for automobile tires, there has been proposed a modified conjugated diene polymer in which an end of a conjugated diene polymer is modified using a compound having an amino group and an alkoxysilyl group (e.g., see Patent Document 1). Moreover, there have been proposed a modified conjugated diene polymer in which a silicon atom is bound to the carbon atom constituting the main chain of the polymer and also an amino group is bound to the silicon atom and a modified conjugated diene polymer in which a benzene ring having an amino group is bound (e.g., see Patent Documents 2 and 3).